Calcitonin: Beyond the Headlines

You may have seen some strongly worded headlines this week about an osteoporosis drug called calcitonin salmon. “FDA Panel Says ‘No’ to Osteoporosis Drug.” “Osteoporosis Drug Ineffective and Dangerous, FDA Reports.” This Tuesday, an FDA Advisory Panel did vote that the benefits of calcitonin salmon were outweighed by an increased risk of cancer the drug may carry, but the story doesn’t stop there, and much remains uncertain.

Osteoporosis is a condition in which bones lose their density and strength over time. While the weakening of bones can be completely painless and go undetected for years, it increases the risk of a potentially serious fracture.

Women who have gone through menopause are at an increased risk for osteoporosis. The hormone calcitonin can slow this deterioration, and calcitonin salmon — a synthetic form of the hormone as it appears in salmon — has long been a treatment option for people with osteoporosis. There has, however, been a decline in the use of calcitonin for osteoporosis, and the drug now accounts for less than 5% of the osteoporosis drugs sold in the United States, according to FDA documents. The same documents say more than 99% of calcitonin prescriptions are for nasal forms of the drug, such as Fortical and Miacalcin.

In recent years, concerns about an increased risk of cancer with the use of calcitonin have begun to surface, as have questions about the drug’s true efficacy. In July of 2012, The European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP) concluded that, while short-term use of calcitonin was reasonably safe for some conditions, it should not be used to treat osteoporosis.

This Tuesday at a joint meeting of the FDA’s Advisory Committee for Reproductive Health Drugs and Drug Safety and Risk Management Advisory Committee, committee members came to similar conclusions about calcitonin’s risks and benefits.

Even if the advisory panel had had the power to decide on behalf of the FDA, a ‘no’ vote would not necessarily have meant pulling calcitonin salmon off the market. And the panel was far from unanimous. For example, although MedPage Today wrote about the decision in an article with the headline “FDA Reviewers Bash Fish Hormone,” it also reported the panel’s vote was 12 to 9. In a telephone conversation with Arthritis Self-Management, one of the panel members called the vote “split.”

Although the FDA generally follows the advice of its advisory panels, it doesn’t always, and it’s not clear what action the FDA will take — if any. The FDA may ban calcitonin altogether, but it may also do as little as change the warnings on the label, or even do nothing at all.

The bottom line: It’s hard to say. The briefing materials the advisory panel received say that calcitonin salmon does seem to increase the risk of cancer somewhat (by about 1.6% or 9%, according to different estimates) but with the data available, it’s difficult to establish a strong causal link. At the same time, although calcitonin does seem to slow the progression of osteoporosis, it doesn’t seem to have an effect on a person’s risk of fractures.

About 57% percent of a 21-person joint panel said calcitonin should no longer be marketed for the treatment of osteoporosis in women at least five years past menopause; about 43% didn’t.

According to the pre-meeting briefing documents, further testing is “problematic” because fewer and fewer people are using calcitonin salmon. What the FDA will actually do, if anything, is not known at this time.

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